A friend asked me to ask here, so I may be on the wrong site, what level's you suggest for The Pcs to be for the final battle with The Campaigns big bad and actual levels for him. Also he's wrote A RPG that's A Legends and Edition 3.5 DAD Hybrid so it sort of counts

The Pcs are currently 11th level, by the final fight in 5.7 real-life weeks or 2.76 in-game years they are guaranteed to be at least 13th level, will more likely then not be at least 15th level, have a fairly high chance of getting to mid-way through 16th level and if they really try hard may just acquire 17th level half a week or so of in-game time before the final fight

He on the other hand has certain minimum and maximum levels in 4 classes. As A Ex Junior Captain Rank Officer in his homelands Primary Army he has to be A Fighter or Barbarian of between 6th level and 8th level, as he is A Grade 2 Member of both The Local Thieves and Wizards Guilds he has to be both A Thief AND A Wizard, but not A Sorcerer, of between 4th and 6th level in both classes and if only A 4th level Wizard has to have a minimum of all 0 level, at least 15 1st level, at least 9 2nd level and at least 3 3rd level Spells on/in his Books and Scrolls and as he once won 2 and secured 2nd place twice more Charity Singing Contest at The Very Amateur grade that are held by his Homelands Armed Forces has to be A Bard of 1st or 2nd level and with the highest possible level of ability in any ability relating to singing

So bearing all that in mind what would you suggest are minimum, maximum and ideal levels for The Big Bad, The Pcs and any allies, loyal or charmed or have a go heroes or villains that turn up in time to give their chosen side a chance, to make this a challenge but neither side is guaranteed to win or guaranteed to lose. Can you please advise?

A friend asked me to ask here, so I may be on the wrong site, what level's you suggest for The Pcs to be for the final battle with The Campaigns big bad and actual levels for him. Also he's wrote A RPG that's A Legends and Edition 3.5 DAD Hybrid so it sort of counts

Legend normally does not have levels, but the rules are a combination of Legend and D&D so you might be on the right site.

Have you looked at The Design Mechanism's Classic Fantasy? That allows you to play using Mythras rules (which are very close to Legend) but with the structures of D&D. There are 5 levels, from memory, so it doesn't have quite the same levels as D&D but looks pretty good to me.

The Pcs are currently 11th level, by the final fight in 5.7 real-life weeks or 2.76 in-game years they are guaranteed to be at least 13th level, will more likely then not be at least 15th level, have a fairly high chance of getting to mid-way through 16th level and if they really try hard may just acquire 17th level half a week or so of in-game time before the final fight

When I played D&D, we struggled to level up through experience, so I am not used to playing at high levels and progressing so quickly.

So bearing all that in mind what would you suggest are minimum, maximum and ideal levels for The Big Bad, The Pcs and any allies, loyal or charmed or have a go heroes or villains that turn up in time to give their chosen side a chance, to make this a challenge but neither side is guaranteed to win or guaranteed to lose. Can you please advise?

It really does depend, as Legend has a different dynamic to D&D.

Normally, in Legend and older versions of RuneQuest, numbers can count, especiially at lower levels, but your party seem to be high level, so numbers are not really an issue. So, I would probably be happy to throw slightly higher numbers of lower-skilled/equipped NPCs at your party. So, if you have 5 party members, you should probably be able to handle 8 opponents, assuming your magic and equipment are good.

In my experience, a well-organised party can take out an equivalent party fairly easily, simply due to better tactics and working together.

As for the Big Bad, it really depends on what it is. If it is a powerful magic user then it would have to have other NPCs supporting it otherwise it would be beaten in combat. If it is a non-human then it might be able to survive as an individual. A Dragon would be a good fight for a high level party. A Great Troll might struggle against a high level party and would need some support from other trolls. A big Giant might be OK on its own, especially if using a tree trunk to sweep the PCs. Other individuals would be cannon fodder for a high level party.

The dynamics of combat in Legend / Mythras are different to those of D&D. Not in a bad way, but the differences can trip you up if you aren't prepared for them.

For one thing, a large number of low-powered bad guys can easily overwhelm a powerful character by sheer weight of numbers. This can be a nasty surprise for D&D veterans, who are used to wading into combat against hordes of lesser foes. My advice is that if you are going to pit the adventurers against a large group of opponents, offer them some kind of tactical advantage - like higher ground or a doorway limiting the number of opponents that can come at them at any given time. If the players are smart enough to use the terrain to their advantage, this helps to even the odds. If they are not, they deserve whatever happens to them.

In any case, rarely pit the adventurers against odds greater than 2 to 1 or the bad guys will wipe the floor with them. Remember that it only takes one lucky hit to incapacitate even the toughest adventurer. If the bad guys get a lot of attacks -- even at low skill ratings -- sooner or later one of them will hit the jackpot. This is a game system where limbs get hacked off and people end up with deadly chest wounds. It's not like D&D where adventurers can take a beating and keep fighting as long as they have a single hit point left.

Conversely, a Big Bad rarely lasts long against a group of experienced adventurers. If the adventurers outnumber the big bad by a significant margin, they will take him down in a round or two. One solution is to give the big bad a retinue of disposable minions who prevent the adventurers from getting too close. The disadvantage of this approach is that players tend to ignore the retinue if they can and focus all of their firepower on the Big Bad. A better approach is to move away from having a single bad guy at the end of the adventure and use a rival group of adventurers. If you build a team of bad guys around the same power level as the PCs, they will give the adventurers a run for their money. One sneaky trick is to use the character sheets of the Player Characters as a starting point to design the opponents. Change a few stats, move a few skill points, and give them a different selection of spells. If you play these "mirror" adventurers as a cohesive unit who have worked out their tactics in advance, they will put some fear into the adventurers. And provided that you change details such as genders, races, and personalities the players will never know how you designed such a tough team of bad guys...